Expandable screens, primarily useful for preventing flys and other insects from penetrating window openings, usually include a pair of adjacent, side-by-side framed screens which are adjustably expandable transversely relative to the window opening. Most of these expandable screens are complex and relatively expensive, requiring tracks or guides built either onto associated window frame members, such as the window's sill or stile, or directly within the screen frames. One sliding screen member is usually of a different construction than the other, thereby increasing the complexity and cost of construction.
For example, the U.S. Pat. No. 813,727 to Marquardt discloses an expandable screen provided with a first screen frame incorporated with dovetailed-ribbed guides for slidably engaging corresponding channels provided in a second, adjacent screen frame. The U.S. Pat. No. 1,701,848 to Hickman also discloses an expandable screen, stated to be particularly useful for automobile windows, including a first screen frame provided with a horizontally extending slot to slidably receive a pin member equipped on a second, adjacent screen fame. These expandable screens, being adjustable, can adapt to window openings of varying widths and eliminate the need for window sill or stile mounted tracks or guides for maintaining the expandable screen within a window opening; in other words, these expandable screens can be positionably lodged within the window frame opening abutted between the window stiles.
While these types of expandble screens are beneficial for trackless placement between window stiles, the screens are equipped with complicated and cumbersome built-in track constructions which prevent simple and quick assemblage of these screens during their installation. Furthermore, these above-mentioned screen types possess an unesthetic exterior appearance, so that the screens are an unattractive window addition to homeowners and the like. In addition, they are unduly complex in construction and therefore expensive to manufacture.
The U.S. Pat. No. 2,408,714 to Whallen discloses an expandable screen including a pair of independent, identical screened frames, both being equipped with brackets or clips which are fastened by screens for cooperation with lower rail of the window sash and for permitting the frames to slide transversely relative to such rail in the window opening. The clips include an L-shaped flanged portion which must be abutted or received by the window sash rail in order for the screened frames to transverse relative to the window opening. This particular expandable screen has many disadvantages. Thus it is only useful when employed in windows of a particular construction.
Insofar as is known, no expandable screen has previously been available which eliminates the need for window stile or sill mounted tracks as well as tracks or guides built directly within the screen frames. Furthermore, there is a great need for an expandable screen frame which is simple in construciton and inexpensive to make, and simple and easy to assemble with other identical screen frames.